A known external skeletal fixation device is used for fixing a fractured bone or for bone deformity correction.
The external skeletal fixation device includes plural rodlike members to be inserted into a bone to be fixed from outside the human body, and clamp members for fixedly holding the rodlike members. An Ilizarov external skeletal fixation device disclosed in, for example, Reference document 1, is a known external skeletal fixation device for bone deformity correction. This known external skeletal fixation device includes plural wires as rodlike members to be inserted into a bone, plural ring frames for holding the wires, and a stretchable connecting mechanism for connecting the clamp members. The external skeletal fixation device is disposed so as to surround a deformity point determined as the center of deformation correction.
The Ilizarov external skeletal fixation device fixes the bone with pins held by the clamp members, distracts or shortens the connecting mechanism and corrects the deformation of the bone at the deformity point by extending or twisting the bone in a direction to correct the deformation.
An external skeletal fixation device, such as disclosed in Patent document 1 for holding bones connected by a joint to reduce load on the joint inserts plural half pins, namely, rodlike members, into the radius and the metacarpus and fixes the wrist.
FIG. 17 shows a known external skeletal fixation device 12
Component members of the external skeletal fixation device 12 are made of a metal.
As shown in FIG. 17, the external skeletal fixation device 12 includes a radius traction member 12A for holding half pins 12A1 inserted into the radius 94A, a metacarpus traction member 12B for holding half pins 12B1 inserted into the metacarpus, and a central block 12C connecting the radius traction member 12a and the metacarpus traction member 12B. The half pins 12A1 and 12B1 are attached to the radius traction member 12A and the metacarpus traction member 12B so as to extend perpendicularly to the respective axes of the radius traction member 12A and the metacarpus traction member 12B, respectively. The half pins 12A1 and 12B1 can slide along the radius traction member 12a and the metacarpus traction member 12B, respectively.
The central block 12C of the external skeletal fixation device 12 holds the radius traction member 12A and the metacarpus traction member 12B so as to be turnable relative to each other. The central block 12C permits the following motions (1) to (3) when the hand is in palm down position.
(1) Bending/stretching motions (turning motions about an axis X of turning) on the joint of the central block 12C and the metacarpus traction member 12B according to the vertical movement of the wrist
(2) Displacement (turning motions about an axis Y or turning) of the radius 94A/the ulna 94B according to lateral motions of the wrist
(3) Pronation/supination (turning motions about an axis Z of turning) on the joint of the radius traction member 12A and the central block 12C according to twisting motions of the wrist
Reference document 1: G. A. Ilizarov, “Transosseous Osteosynthesis: Theoretical and Clinical Aspect of the Regeneration and Growth of Tissue” Springer-Verlag, 1992 Patent document 1: JP 2001-524859 A (FIG. 2)